Requirements relating to the design and manufacture of road vehicles in the United States have been greatly influenced by regulations issued by the U.S. Department of Transportation. As a consequence, the development of improved brake assemblies has been occurring over a considerable period of time. Increased brake designer attention has been given to meeting governmental vehicle brake system operating requirements, particularly as expressed in vehicle stopping distance specifications. Such has resulted in the publication of at least one known brake assembly construction utilizing two opposed brake friction pads fabricated using different friction material compositions. Specifically, U.S. Pat. No. 3,856,120 discloses a vehicle disc brake assembly invention made jointly by myself and Patrick A. Thesier which includes both a semi-metallic friction pad and an organic friction pad, the organic friction pad containing asbestos fibers in the range of from 20 to 60 percent by volume.
However, in order to avoid asbestos-containing compositions in the manufacture and use of brake system friction pads it becomes necessary to devise new friction material formulations. In the process I have discovered that new brake assembly and brake system operating characteristics such as increased cold stopping and reduced noise generation may be realized with particular new friction pad material combinations.
Other brake system advantages also may be realized through the practice of my invention.